chore(mongodb-downloader): use a lockfile to prevent redundant parallel downloads

Author: gagik

package-lock.json

@@ -53,10 +53,12 @@
   },
   "dependencies": {
     "debug": "^4.4.0",
-    "tar": "^6.1.15",
     "decompress": "^4.2.1",
-    "mongodb-download-url": "^1.6.3",
-    "node-fetch": "^2.7.0"
+    "node-fetch": "^2.7.0",
+    "promise-retry": "^2.0.1",
+    "signal-exit": "^4.1.0",
+    "tar": "^6.1.15",
+    "mongodb-download-url": "^1.6.3"
   },
   "devDependencies": {
     "@mongodb-js/eslint-config-devtools": "0.9.12",
@@ -67,6 +69,8 @@
     "@types/decompress": "^4.2.4",
     "@types/mocha": "^9.1.1",
     "@types/node": "^22.15.30",
+    "@types/promise-retry": "^1.1.6",
+    "@types/signal-exit": "^3.0.4",
     "@types/tar": "^6.1.5",
     "depcheck": "^1.4.7",
     "eslint": "^7.25.0",

packages/mongodb-downloader/package.json

@@ -0,0 +1,128 @@
+import { expect } from 'chai';
+import { promises as fs } from 'fs';
+import path from 'path';
+import os from 'os';
+import { MongoDbDownloader } from './index';
+
+describe('downloader with Locking', function () {
+  this.timeout(60000);
+
+  let tmpDir: string;
+
+  beforeEach(async function () {
+    tmpDir = path.join(os.tmpdir(), `download-integration-tests-${Date.now()}`);
+    await fs.mkdir(tmpDir, { recursive: true });
+
+    // No mocking - let tests download real MongoDB binaries
+  });
+  const version = '8.2.0';
+
+  afterEach(async function () {
+    try {
+      await fs.rm(tmpDir, { recursive: true });
+    } catch {
+      // Ignore cleanup errors
+    }
+  });
+
+  it('should prevent concurrent downloads of the same version', async function () {
+    const downloader = new MongoDbDownloader({ tmpdir: tmpDir });
+
+    const results = await Promise.all([
+      downloader.downloadMongoDbWithVersionInfo(version),
+      downloader.downloadMongoDbWithVersionInfo(version),
+      downloader.downloadMongoDbWithVersionInfo(version),
+    ]);
+
+    // All results should be identical
+    expect(results[0].version).to.equal(version);
+    expect(results[1].version).to.equal(version);
+    expect(results[2].version).to.equal(version);
+
+    expect(results[0].downloadedBinDir).to.equal(results[1].downloadedBinDir);
+    expect(results[1].downloadedBinDir).to.equal(results[2].downloadedBinDir);
+
+    // Verify the downloaded directory exists and contains mongod
+    expect(await fs.stat(results[0].downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(results[0].downloadedBinDir, 'mongod'))).to
+      .be.ok;
+  });
+
+  it('should wait for existing download to complete', async function () {
+    // First, download MongoDB normally
+    const downloader = new MongoDbDownloader({ tmpdir: tmpDir });
+    const result = await downloader.downloadMongoDbWithVersionInfo(version);
+
+    expect(result.version).to.equal(version);
+    expect(result.downloadedBinDir).to.be.a('string');
+
+    // Verify the downloaded directory exists and contains mongod
+    expect(await fs.stat(result.downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(result.downloadedBinDir, 'mongod'))).to.be
+      .ok;
+  });
+
+  it('should skip download if already completed', async function () {
+    // First download
+    const downloader = new MongoDbDownloader({ tmpdir: tmpDir });
+    const result1 = await downloader.downloadMongoDbWithVersionInfo(version);
+
+    // Second download should use cached result
+    const result2 = await downloader.downloadMongoDbWithVersionInfo(version);
+
+    expect(result1.version).to.equal(version);
+    expect(result2.version).to.equal(version);
+    expect(result1.downloadedBinDir).to.equal(result2.downloadedBinDir);
+
+    // Verify the downloaded directory exists and contains mongod
+    expect(await fs.stat(result1.downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(result1.downloadedBinDir, 'mongod'))).to.be
+      .ok;
+  });
+
+  it('should handle different versions independently', async function () {
+    const version2 = '8.1.0';
+
+    // Download different versions
+    const downloader = new MongoDbDownloader({ tmpdir: tmpDir });
+    const [result1, result2] = await Promise.all([
+      downloader.downloadMongoDbWithVersionInfo(version),
+      downloader.downloadMongoDbWithVersionInfo(version2),
+    ]);
+
+    expect(result1.version).to.equal(version);
+    expect(result2.version).to.equal(version2);
+    expect(result1.downloadedBinDir).to.not.equal(result2.downloadedBinDir);
+
+    // Verify both downloaded directories exist and contain mongod
+    expect(await fs.stat(result1.downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(result1.downloadedBinDir, 'mongod'))).to.be
+      .ok;
+    expect(await fs.stat(result2.downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(result2.downloadedBinDir, 'mongod'))).to.be
+      .ok;
+  });
+
+  it('should handle promise caching correctly', async function () {
+    const version = '8.2.0';
+
+    // Start multiple downloads in sequence (not parallel)
+    const downloader = new MongoDbDownloader({ tmpdir: tmpDir });
+    const result1 = await downloader.downloadMongoDbWithVersionInfo(version);
+    const result2 = await downloader.downloadMongoDbWithVersionInfo(version);
+    const result3 = await downloader.downloadMongoDbWithVersionInfo(version);
+
+    // All should return the same result
+    expect(result1.version).to.equal(version);
+    expect(result2.version).to.equal(version);
+    expect(result3.version).to.equal(version);
+
+    expect(result1.downloadedBinDir).to.equal(result2.downloadedBinDir);
+    expect(result2.downloadedBinDir).to.equal(result3.downloadedBinDir);
+
+    // Verify the downloaded directory exists and contains mongod
+    expect(await fs.stat(result1.downloadedBinDir)).to.be.ok;
+    expect(await fs.stat(path.join(result1.downloadedBinDir, 'mongod'))).to.be
+      .ok;
+  });
+});